Generalised the osgDB::Field so that its getFloat() method can be used with either doubles or
floats governed by the type passed in - this helps support either float/double
Quat and Matrix classes seemlessly.
memory manager published at flipcode.com. This can be turned on
with the OSG_USE_MEMORY_MANGER option which then uses custom global
new and delete operators as well as provide osgNew and osgDelete macro's
which add ability to log line and file from which calls are made.
Updated osg,osgUtil,osgDB,osgText and osgPlugins/osg to use osgNew/osgDelete,
and fixed memory leaks highlighted by the new memory manager.
